/Engine/Source/Editor/UnrealEd/Public/IProjectExternalContentInterface.h
Adds a reference to external content to the project and asynchronously downloads/loads the external content
void AddExternalContent ( const [FString](API\Runtime\Core\Containers\FString) & ExternalContentId, [FAddExternalContentComplete](API\Editor\UnrealEd\IProjectExternalContentInterface\FAddExternalContentComplete) CompleteCallback )